1. Field of the Invention
The present invention relates generally to agricultural harvesters such as combines, and more particularly to threshing or separating systems of such combines, and still more particularly to systems or structures for securing concaves in the threshing systems of such combines.
2. Description of the Related Art
An agricultural harvester known as a “combine” is historically termed such because it combines multiple harvesting functions, such as picking or cutting, threshing, separating and cleaning in a single harvesting machine. A typical combine includes a header which removes the crop from a field, and a feeder housing which transports the crop matter into a threshing rotor. The threshing rotor rotates within a perforated housing, which may be in the form of adjustable concaves, and performs a threshing operation on the crop, to dislodge the grain from other crop material. Once the grain is threshed, it falls through perforations in the concaves onto a grain pan. From the grain pan, the grain is cleaned on sieves in a cleaning system. A cleaning fan blows air through the sieves to discharge chaff and other debris toward the rear of the combine. Non-grain crop material, such as straw from the threshing system, proceeds through a residue system, which may utilize a straw chopper to process the non-grain material and direct it out the rear of the combine. The cleaned grain is transported to a grain tank onboard the combine. When the grain tank becomes full, the combine is positioned adjacent a vehicle into which the grain is to be unloaded, such as a semi-trailer, gravity box, straight truck, or the like; and an unloading system on the combine is actuated to transfer the grain from the grain tank into the vehicle.
More particularly, a rotary threshing or separating system includes one or more rotors which can extend axially (front to rear) or transversely (side to side) within the body of the combine, and which are partially or fully surrounded by a perforated concave. The crop material is threshed and separated by the rotation of the rotor within the concave. Coarser non-grain crop material such as stalks and leaves are transported to the rear of the combine and discharged back to the field. The separated grain, together with some finer non-grain crop material such as chaff, dust, straw, and other crop residue are discharged through the concaves and fall onto a grain pan where they are transported to the cleaning system. Alternatively, the grain and finer non-grain crop material may also fall directly onto the cleaning system itself.
The cleaning system further separates the grain from non-grain crop material, and typically includes a fan directing an airflow stream upwardly and rearwardly through vertically arranged sieves which oscillate in a fore and aft manner. The airflow stream lifts and carries the lighter non-grain crop material towards the rear end of the combine for discharge to the field. Clean grain, being heavier, and larger pieces of non-grain crop material, which are not carried away by the airflow stream, fall onto a surface of an upper sieve (also known as a chaffer sieve) where some or all of the clean grain passes through to a lower sieve (also known as a cleaning sieve). Grain and non-grain crop material remaining on the upper and lower sieves are physically separated by the reciprocating action of the sieves as the material moves rearwardly. Any grain and/or non-grain crop material remaining on the top surface of the upper sieve is discharged at the rear of the combine. Grain falling through the lower sieve lands on a bottom pan of the cleaning system, where it is conveyed forwardly toward a clean grain auger. The clean grain auger conveys the grain to a grain tank for temporary storage.
The concaves of the combine threshing system need to be changed for harvesting different types of crops. For optimum performance, concaves need to be replaced if excessively worn or damaged. It is known to secure concaves using threaded fasteners, such as bolts and the like, which require tools both for releasing the fasteners to disengage a concave for removal and to engage and tighten the fasteners to secure a replacement concave in position. Removing and replacing concaves with known securing systems can be difficult and time-consuming under shop conditions and even more difficult if performed in the field during a harvesting operation, when time is critical and nonproductive harvesting time is costly.
What is needed in the art is a concave securing system that can be operated more efficiently under typically experienced conditions to facilitate removal and installation of concaves in an agricultural harvester.